Some electronic devices are manufactured using the following four layer structure, listed in order of deposition on a substrate: tantalum nitride (TaN), tantalum (Ta), copper seed (Cu-seed) and copper (Cu). Such a structure may require four deposition steps, with each step taking time to employ, requiring the use of potentially hazardous reagents and resulting in potentially hazardous effluent. In order to reduce the number of deposition steps, some manufacturers have substituted ruthenium for tantalum. This substitution has enabled the manufacturers to eliminate the copper seed layer, which may be used only to enable copper to be deposited on tantalum. As copper can be deposited directly on ruthenium, a seed layer may not be necessary, and the structure may be created using only three deposition steps.
Accordingly, it is desirable to have a method for cleaning built up ruthenium from deposition equipment and to recover the ruthenium for re-use in the manufacture of electronic devices.